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Published May 11, 2023 | Version v1
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Fish on fire: Shifts in Amazonian fish communities after floodplain forest fires

Authors/Creators

  • 1. Wageningen University & Research
  • 2. National Institute of Amazonian Research

Description

  1. Severe droughts can lead to fires that cause massive tree mortality in even the wettest and most isolated Amazonian forests. After repeated fires, blackwater floodplain forests can remain in an open vegetation state of arrested succession that facilitates a transition towards a white-sand "savanna-like" vegetation. These vegetation shifts from closed-canopy floodplain forests to open fire scars, and eventually white-sand savannas, may have profound implications for fish communities that depend on floodplain forests for food and recruitment. In turn, changes in fish communities may contribute to the arrested forest recovery after fires as fish are important seed dispersal agents for many floodplain tree species.
  2. To explore the impacts of floodplain forest fires on fish communities, we sampled fish in unburnt forests, fire scars, and white-sand savannas in the middle Rio Negro basin (Brazil) during two consecutive flooding seasons. We compared the abundance, species richness, and the taxonomic and trophic composition of fish assemblages across the three habitat types. 
  3. We found significant shifts in fish assemblages in fire scars compared to unburnt floodplain forests. Also, as fire scars increased in size, total fish biomass decreased strongly. Fish communities in unburnt floodplain forests seem to be characterized by a higher proportion of smaller and omnivorous fish species than fish communities in burned floodplain forests and white sand savannas. Fish assemblages in fire scars and white-sand savanna were not significantly different.
  4. Synthesis and Applications. Amazonian fish communities change after floodplain forest fires. Unburnt forests have diverse fish communities, with a large proportion of unique and small omnivorous species. In contrast, carnivores and detritivores become more common in fire scars and white-sand savannas formed after forest fires. Less omnivore fish after forest fires can reduce tree seed dispersal and forest regeneration, affecting ecosystem functioning and the services provided by Amazonian forests. Fish are also a primary source of food and income for people living in Amazonian floodplains. Preventing forest fires is therefore of fundamental importance for the conservation of Amazonian aquatic and terrestrial ecological communities as well as for the livelihood of people. 

Notes

Funding provided by: National Geographic Society Education Foundation
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100001257
Award Number: NGS-165R-18

Funding provided by: Wageningen University Fund
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100004891
Award Number:

Funding provided by: Fundação de Amparo à Pesquisa do Estado do Amazonas
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100004916
Award Number:

Funding provided by: European Commission
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100000780
Award Number: MSCA-IF 746181

Funding provided by: Conselho Nacional de Desenvolvimento Científico e Tecnológico
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003593
Award Number: 313183/2014-7

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